The combination microelectronic mechanical systems (MEMS) and integrated circuits (ICs) allows for the possibility to make any number of micro-sensors, transducers and actuators. Unfortunately, typical methods for making MEMS are incompatible methods used to fabricate ICs. Hence, MEMS and ICs are usually fabricated separately and laboriously combined in subsequent and separate steps.
In addition to the MEMS and ICs processing incompatibilities, MEMS typically require encapsulation, whereby the active portions of the MEMS are sealed within a controlled storage environment. One way to encapsulate the active portions of the MEMS is to provide unique customized packaging structure configured with conductive leads fitted for the MEMS. Alternatively, the MEMS can be formed on a wafer substrate that serves as a bottom portion of the packaging structure. After the MEMS is formed on the wafer, then a matched lid structure is glued or soldered over the active potions of the MEMS within the suitable storage environment. For example, Shook describes a method and apparatus for hermetically passivating a MEMS on a semi-conductor substrate in U.S. patent application Ser. No. 09/124,710, and also U.S. patent application Ser. No. 08/744,372, filed Jul. 29, 1998 and entitled METHOD OF AND APPARATUS FOR SEALING A HERMETIC LID TO A SEMICONDUCTOR DIE, the contents of both of which are hereby incorporated reference.
What is needed is a method to make MEMS and other structures on a wafer substrates utilizing processes that are compatible with standard IC wafer processing, whereby MEMS and ICs are capable of being fabricated on the same wafer chip. Further, what is needed is a method to fabricate MEMS, wherein the active portions of the MEMS are readily encapsulated within a variety of suitable storage environments.